Hydroaccumulator, in particular a bladder accumulator

ABSTRACT

The invention relates to a hydroaccumulator, in particular a bladder accumulator. Said accumulator comprises a pressurised container ( 1 ), a separation element ( 5 ) which is located in said container and separates a gas chamber ( 7 ) in the pressurised container ( 1 ), lying adjacent to an inlet on the gas side from a fluid chamber ( 9 ), lying adjacent to an inlet on the fluid side ( 3 ), said inlet having a fluid connecting sleeve ( 11 ) and a valve arrangement located on the connecting sleeve ( 11 ), said arrangement having at least one valve body ( 17 ) that has a transversal bore ( 33 ). The valve body is usually pretensioned in an open position which allows the passage of fluid and can be displaced into a closed position by a displacement of the separation element ( 5 ), the interior surface ( 15 ) of the connecting (sleeve ( 11 ), which lies directly against the valve body ( 17 ), guiding the displacement of said body between the open and closed positions. As the side of the valve body ( 17 ′) that faces the separation element ( 5 ) is configured as a plate running on one plane, as the respective transversal bore ( 33 ), which is delimited by the plate ( 17 ′) in the open position, opens at least partially into the fluid chamber ( 9 ) and as the diameter of the valve body ( 17 ) is greater than its height, measured in the direction of displacement of said valve body ( 17 ), the valve arrangement has a plate-valve construction of small proportions and can be cost-effectively produced.

[0001] The invention relates to a hydroaccumulator, in particular a bladder accumulator, with a pressure tank, a separating element which is located in it and which separates in the pressure tank a gas space which borders a gas-side access from a fluid space which borders the fluid-side access which has a fluid connecting sleeve, and with a valve arrangement which is located on the connecting sleeve with a valve body which has at least one transverse hole and which is normally pretensioned into its open position which clears the fluid passage, and can be moved into its closed position by the displacement of the separating element, the inside surface of the connecting sleeve for the valve body directly adjoining it forming the guide for its displacement between the open position and the closed position.

[0002] Hydraulic accumulators of this type are commercially available. In the technical reference published by Mannesmann Rexroth GmbH “Hydraulic Guide Volume 1” on page 165 a bladder accumulator of the aforementioned type is depicted and described. In the known bladder accumulator the valve arrangement is made as a seat valve, on the end edge of the connecting sleeve facing the fluid space, as the stationary valve seat, a conical surface being formed which interacts with the corresponding conical surface on the valve plate of the movable valve body. It is made similarly to the control valves which are conventional in valve-controlled internal combustion engines, i.e., the valve plate is located on a shaft which is guided in a valve guide for the valve lifting motion which runs between the open position and closed position, and the valve guide is installed in the connecting sleeve.

[0003] The disadvantage here is the resulting high production costs due to the required cost for producing and machining of a host of individual parts as a result of this valve design. In order to ensure proper operation of the valve arrangement, the valve guide installed in the connecting sleeve must be made carefully with respect to production tolerances, both alignment and fit. Moreover the corresponding machining of the conical surfaces which form the valve seat is necessary.

[0004] PCT/WO 00/31420 discloses a generic hydraulic accumulator with a separating element formed from metal bellows. Within the bellows is a compression spring which keeps the separating element in the pretensioned state. On the bottom the bellows is provided with an end plate which interacts with a valve body which is accommodated in the fluid connecting sleeve of the housing of the known hydraulic accumulator, held under spring pretension. The valve body is made as a valve lifter and is larger in dimensions in its lengthwise alignment than in the transverse direction, so that the known valve body occupies considerable space in its direction of displacement in the connecting sleeve. The end of the valve body which interacts with the end plate is made dome-like so that in conjunction with the different diameters, grooves and recesses, beveled surfaces and the transverse hole on the other end of the valve body a complex geometry forms which requires a complex and costly machining process in production. The complex geometrical structure of the closing body continues in the area of the fluid guide and as a result of the repeated deflection of the fluid flow especially in the area of the incident flow of the medium into the fluid space, unfavorable flow behavior is obtained so that the known approach to hydraulic accumulators with sensitive membrane bladders is not suitable.

[0005] Proceeding from the proximate art, the object is to further improve the known hydraulic accumulator such that the valve body occupies little space, that it is geometrically simple in structure and moreover can be economically implemented, and allows optimized flow behavior in the area of the flow into the fluid space. The object is achieved by a hydraulic accumulator with the features of claim 1 in its entirety.

[0006] By virtue of the fact that according to the characterizing part of claim 1 the valve body on its side facing the separating element is made as a plate which runs flat, that the respective transverse hole bordered by the plate in the open position discharges at least partially into the fluid space and that the diameter of the valve body is larger than its height measured in the direction of displacement of the valve body, the valve arrangement is made in the manner of a plate valve which occupies little space and which can be economically implemented. The fluid channels required for triggering of the fluid flow are completely integrated into the interior of the valve body so that complex machining for differentiated shaping of the outside surface of the valve body is eliminated. Since the respective transverse hole underneath the valve body plate which runs flat discharges into the fluid space in the open position, homogeneous outflow behavior of the fluid into the fluid space is ensured, so that especially when a bladder accumulator is implemented flow takes place carefully around the separating membrane which is sensitive to pressure peaks and which ordinarily consists of a rubber-elastic material; this leads to an increase of the service life of the hydraulic accumulator as claimed in the invention.

[0007] Production is especially simple if the valve arrangement is made in the manner of a sliding valve and the connecting sleeve which is used as the valve housing with its circular cylindrical inside surface defines the piston bore for the valve body which is made as a sliding piston.

[0008] In these embodiments the arrangement can be such that the end edge of the piston bore of the connecting sleeve, which edge borders the fluid space, forms the control edge for clearing and closing one or more fluid channels of the sliding piston.

[0009] The number and cross-sectional size of the holes which are made in the sliding piston and which are used as fluid channels can be chosen such that as fluid passes, the desired choking takes place, so that when the hydraulic accumulator is in operation, depending on the intended application, damping conditions which are optimum in the case arise.

[0010] The piston bore which guides the sliding piston can preferably have on its end area adjacent to the fluid space a tapered hole section through which an annular shoulder surface is formed which in interaction with an opposing shoulder surface which projects radially on the sliding piston forms a stop against which the sliding piston rests in the open position of the valve.

[0011] The invention is detailed below using the embodiments shown in the drawings.

[0012]FIG. 1 shows a cutaway lengthwise section of one embodiment of the bladder accumulator as claimed in the invention, only the part of the accumulator adjacent to the fluid-side connecting sleeve, with the valve arrangement which is in the open position and which is assigned to the connecting sleeve, being shown;

[0013]FIG. 2 shows a lengthwise section of only the fluid connecting sleeve of a second embodiment on a much larger scale compared to FIG. 1, the valve arrangement being shown in the closed position, and

[0014]FIG. 3 shows a section similar to FIG. 1, on the left side and the right side a third embodiment and fourth embodiment being shown and the valve arrangement being shown in the open position.

[0015] In the drawing from FIG. 1, of the pressure tank 1 only the section adjacent to the fluid-side access 3 is being shown. On the opposite end area of the pressure tank 1 which is not shown, there is a conventionally configured gas-side access to the interior space of a storage bladder 5 which is only suggested in FIG. 3, and which forms the movable separating element which separates the gas space 7 located in its interior from the fluid space 9.

[0016] In the embodiment shown in FIG. 1, as the fluid-side access 3 a fluid connecting sleeve 11 on the adjacent end of the fluid space 9 is welded into the wall of the pressure tank 1. The connecting sleeve 11 is made in the form of a circularly cylindrical sleeve which in the section which adjoins its free outer end has an inside thread 13 for the connection of a fluid line which is not shown. In the end area adjacent to the fluid space 9 the connecting sleeve 11 forms a piston bore 15 in which a sliding piston 17 is movably guided. The connecting sleeve 11 thus forms the valve housing for a sliding valve with the sliding piston 17 which is used as the movable valve body and which is guided on the inside surface of the piston bore 15 of the connecting sleeve 11 directly for its displacement along the lengthwise axis 19 of the piston bore 15 and can be moved between the open position shown in FIGS. 1 and 3 and the closed position shown in FIG. 2.

[0017] The sliding piston 17 is pretensioned by a helical compression spring 21 into the open position which is shown in FIGS. 1 and 3. From this position it can be moved with the corresponding expansion of the storage bladder 5 against the force of the compression spring 21 into the closed position which is shown in FIG. 2 when it presses against the top 23 of the accumulator piston 17.

[0018] The compression spring 21 is supported with its end facing away from the sliding piston 17 on a support plate 25 which adjoins the shoulder which is located on the adjacent end of the piston bore 15 in the connecting sleeve 11, and in the embodiment from FIG. 1 is held by a retaining ring 27. In the alternative example from FIG. 2 the support plate 25 is secured by means of a flat snap ring 29. Aside from this difference, the embodiment from FIG. 2 corresponds to that of FIG. 1.

[0019] The compression spring 21 which is tensioned between the support plate 25 and the sliding piston 17 extends into an axial hole 31 which is made in the sliding piston 17, concentrically to the lengthwise axis 19, on its end facing away from the fluid space 9, and discharges into transverse holes 33 in the sliding piston 17. These transverse holes run radially in the vicinity of the top 23 of the sliding piston 17 and at a right angle to one another so that they intersect on the lengthwise axis 19. These transverse holes 33 in the sliding piston 17 form fluid channels which interact with the valve control edge and which form the fluid access to the fluid space 9 by way of the axial hole 31 of the sliding piston 17 and the through holes 35 in the support plate 25 when the sliding valve is in the open position shown in FIGS. 1 and 3.

[0020] In the position of the sliding piston 17 shown in FIG. 2, the orifices of the transverse hole 33 are closed by the control edge the connecting sleeve 11 which is used as the valve housing, which control edge is formed on the upper end edge 37, see FIG. 2. As can be seen from this figure, the piston bore 15 in its end section forms a tapered bore section with its annular shoulder surface 39 which in interaction with an opposing shoulder surface 41 which is provided on the sliding piston 17 (see FIG. 2) forms a stop which limits the displacement of the sliding piston 17 in the direction to the fluid space 9. FIG. 1 shows the corresponding position of the sliding piston 17 fixed by this stop means.

[0021] In the two embodiments shown in FIG. 3, the support plate 25 which is formed as an abutment for the compression spring 21 is provided with an outside thread and is screwed into an inside thread 13 which is formed in the connecting sleeve 11.

[0022] In the embodiment shown on the left side in FIG. 3, the connecting sleeve 11 in the section adjacent to the end edge 37 has an outside thread 43 which is screwed to the corresponding inside thread of the wall of the pressure tank 1. The wall thickness of the pressure tank 1 is made greater in the threaded area for this purpose.

[0023] The embodiment shown on the right side in FIG. 3 has a connecting sleeve 11 which is molded on the pressure tank 1 in one piece by hot or cold forming and otherwise does not differ from the example shown on the left side in the same figure.

[0024] The invention is described above using embodiments in the form of bladder accumulators. But it goes without saying that the invention can be equally used advantageously in hydraulic accumulators of a different design, for example in membrane accumulators or piston accumulators. 

1. Hydroaccumulator, in particular a bladder accumulator, with a pressure tank (1), a separating element (5) which is located in it and which separates in the pressure tank (1) a gas space (7) which borders a gas-side access from a fluid space (9) which borders the fluid-side access (3) which has an fluid connecting sleeve (11), and with a valve arrangement which is located on the connecting sleeve (11) with a valve body (17) which has at least one transverse hole (33) and which is normally pretensioned into its open position which clears the fluid passage, and can be moved into its closed position by the displacement of the separating element (5), the inside surface (15) of the connecting sleeve (11) for the valve body (17) directly adjoining it forming the guide for its displacement between the open position and the closed position, characterized in that the valve body (17) on its side facing the separating element (5) is made as a plate (17′) which runs flat, that the respective transverse hole (33) bordered by the plate (17′) in the open position discharges at least partially into the fluid space (9) and that the diameter of the valve body (17) is larger than its height measured in the direction of displacement of the valve body (17).
 2. The hydraulic accumulator as claimed in claim 1, wherein the valve arrangement is made in the manner of a sliding valve and the connecting sleeve (11) which is used as the valve housing with its circular cylindrical inside surface defines the piston bore (15) for the valve body which is made as a sliding piston (17).
 3. The hydraulic accumulator as claimed in claim 2, wherein the sliding piston (17) has at least one transverse hole (33) which runs transversely to the lengthwise axis (19) of the piston bore (15) as a fluid channel which can be connected to the fluid space (9) and at least one axial hole (31) which runs in the axial direction and which discharges into the transverse hole (33) and which is open on the side of the sliding piston (17) facing away from the fluid space (9), and wherein the end area of the connecting sleeve (11), which edge borders the fluid space (9), forms the control edge for clearing and closing the opening of the transverse hole (33).
 4. The hydraulic accumulator as claimed in claim 3, characterized by a support plate (25) which is anchored in the piston bore (15) on the side of the sliding piston (17) facing away from the fluid space (9), which is cut by at least one through hole (35), and which is used as the abutment for a spring arrangement (21) which is clamped between the latter and the sliding piston (17) for producing the pretensioning force which displaces the sliding piston (17) into the open position.
 5. The hydraulic accumulator as claimed in one of claims 2 to 4, wherein the number and cross-sectional size of the holes (31, 33) which run in the sliding piston (17) in the axial direction and/or in the transverse direction are chosen with regard to the desired choking which results when the fluid passes through.
 6. The hydraulic accumulator as claimed in claims 4 and 5, wherein the spring arrangement has a helical compression spring (21) and wherein the axial hole (31) which is located centrally in the sliding piston (17) with its end area which discharges into at least one transverse hole (33) is used as an abutment for the helical compression spring (21) which fits into the axial hole (31) and which is clamped between the support plate (25) and the sliding piston (17).
 7. The hydraulic accumulator as claimed in one of claims 2 to 6, wherein the piston bore (15) on its end area (37) adjacent to the fluid space (9) has a tapered bore section for forming an annular shoulder surface (39) which in interaction with an opposing shoulder surface (41) which projects radially on the sliding piston (17) forms a stop against which the sliding piston (17) rests in the open position under the influence of the pretensioning force acting on it.
 8. The hydraulic accumulator as claimed in one of claims 2 to 7, wherein the sliding piston (17) in the vicinity of its end facing the fluid space (9) has two transverse holes (33) which run continuously to one another at a right angle and which intersect on the central lengthwise axis (19) of the sliding piston (17).
 9. The hydraulic accumulator as claimed in one of claims 1 to 8, wherein the connecting sleeve (11) is welded into the end-side opening of the pressure tank (1).
 10. The hydraulic accumulator as claimed in one of claims 1 to 8, wherein a connecting sleeve (11) on one end of the pressure tank (1) is molded onto the tank in one piece by hot or cold forming.
 11. The hydraulic accumulator as claimed in one of claims 1 to 8, wherein the connecting sleeve (11) has an outside thread (43) in its section facing the fluid space (9) and is screwed to the inside thread in the assigned end-side position of the pressure tank (1).
 12. The hydraulic accumulator as claimed in claim 4 and one of the other claims 1 to 11, wherein the connecting sleeve (11) in the section adjoining the piston bore (15) on the side facing away from the fluid space has an inside thread (13) into which the support plate (25) which is provided with an outside thread is screwed. 